MI will start immediately when the sample is going to start the exercise program. The intervention group will undergo 24 sessions of imagery, starting from the 1st exercise program session. Participants of the intervention group will undergo a 45-minute imagery session sitting in a quiet place after the end of every exercise program session. The content of every imagery session is alike with the content of the exercise program session. That means that every session includes imagery of the same exercises of the exercise program performed earlier by the subject in the Day Center. Sessions are identical for all subjects of the intervention group. The total duration of the physiotherapy exercise program will be 24 sessions, 2 times/week, duration of 45 minutes each session, 3 months (12 weeks).

The total duration of the physiotherapy exercise program will be 24 sessions, 2 times/week, duration of 45 minutes each session, 3 months (12 weeks).

Mental imagery and exercise program will be used to improve balance, functional status, cognitive ability, depression and quality of life of the sample

The Berg Balance Scale (BBS) is used to objectively determine a subject's ability to safely balance during a series of predetermined tasks. It is a 14 item list with each item consisting of a 5-point ordinal scale ranging from 0 to 4, with 0 indicating the lowest level of function and 4 the highest level of function and takes approximately 20 minutes to complete.

The Multidirectional Reach Test (Reach in Four Directions Test) is a screening tool to determine the limits of stability of subjects in 4 directions: forward, backward, leftward and rightward. Subjects performed maximal outstretched arm reach in each direction with their feet flat on the floor.

The Five Times Sit-to-Stand Test (FTSST) is considered to be a useful, consistent and low-cost tool to assess sit-to-stand ability. The FTSST measures the time taken to stand five times from a sitting position as quickly as possible that measures of lower limb strength, balance control and exercise capacity.

The Timed Up and Go test (TUG) is a simple test used to assess a person's mobility. It measures the time that a subject takes to rise from a chair, walk three meters, turn around 180 degrees, walk back to the chair, and sit down while turning 180 degrees.

The Walking While Talking Test (WWITT) is a dual-task measure to examine cognitive-motor interactions. During the WWTT, subjects walk at self-paced speed for 6 meters before turning and walking back to the starting point. During the walking subjects recite 12 Greek alphabet letters (each letter at each step) starting with "A" (ΑΒΓΔ, ΚΛΜΝ, ΠΡΣΤ) until the starting point. Time and errors in the alphabet will be recorded.